There are new essences: Empowered Mithrin (rare, tier 12). These are about 10% more than Mithrin essences (except Vitality, which is only 6.3% more).
An Empowered Mithrin essence box can be crafted using a Universal Solvent, a Dwarrowgleam Shard, and some ordinary mats. It's an automatic Ironfold recipe. The essence box and whichever essence you extract are bound to account.
Individual essences can be unslotted from gear by paying 1 Mithril Coin each.
Among other changes, Beornings will be able to use Heavy Armour.
Embers barter gear has not changed. The devs have said that better gear that drops from the raid will not be available in lootboxes or for barter for some period of time. Although raid-quality gear might drop in lootboxes eventually, it will probably not be available for barter unless you have done the raid.
Your LIs automatically will get 2 more tiers for the main and other legacies. You will also be able to add 3 more star-lit crystals per LI and 3 more empowerment scrolls per legacy.